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Anesthesia Pharmacology > Histamine, Serotonin, Antacids... > Flashcards

Histamine, Serotonin, Antacids... Flashcards

1
Q

Does histamine cross the blood brain barrier?

A

No

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2
Q

What are the effects of histamine on H1 receptors?

A

REspiratory and GI smooth muscle contraction
Pruritis/sneezing
NO release by vascular smooth muscle

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3
Q

What are the effects of histamine bound to H2 receptor?

A

Increased GI secretion of H+

Increased HR/contractility

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4
Q

What is the effect of histamine on the H3 receptor?

A

decreased histamine synthesis and release

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5
Q

What are 5 generalized effects of histamine?

A 
Dilation of arterioles and capillaries
flushing
decreased systemic vascular resistance
decreased BP
increased Capillary permeability
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6
Q

H1 activation occurs at higher concentratrations of histamine than H2. T or F

A

false

H1 activation occurs at lower concentrations

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7
Q

T/F H1 activation decreases AV Node conduction

A

true

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8
Q

H1 activation causes coronary artery _________ while H2 activation causes coronary artery ______________

A

vasoconstriction

vasodilation

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9
Q

How does H2 activation affect the heart?

A

Causes catecholamine release from adrenal medulla
increases HR and contractility
coronary artery vasodilation

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10
Q

How does the skin respond to histamine?

A

dilated capillaries in affected area
Edema-increased capillary permeability
Wheal-dilated arteriols around edema

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11
Q

How do histamine antagonists work to treat allergic reaction?

A

block edema and pruritis but don’t block hypotension–give epi

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12
Q

t/f Histamine blockers act on both H1 and H2 receptors , are competitive inhibitors and are well absorbed orally.

A

F–act on one receptor or the other, not both

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13
Q

What is the difference in first and second generation H1 blockers?

A

First generation also activate muscarinic cholinergic, serotonin and alpha receptors and can cause significant sedation.
Second generation H1 blockers act only on H1 receptors and cause much less sedation

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14
Q

At high doses Second generation H1 receptors may become ______________

A

non-competitive

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15
Q

What are side effects of first generation H1 blockers?

A 
Somnolence
Decreased alertness
slowed rxn time
Dry mouth
Blurred vision
urinary retention
impotence
tachycardia
Dysrythmias
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16
Q

What are teh side effects of second generation H1 blockers?

A

Q-T prolongation at high doses

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17
Q

What are clinical uses for H1 blockers?

A

Rhinoconjuctivitis
Bronchospasm (pretreat)
Anaphylactic/anaphylactoid rxns
motion sickness

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18
Q

Name 4 H2 blockers and their potency

A

Cimetidine (tagamet) potency=1
ranitidine (zantac) potency = 10
famotidine (pepcid) potency = 50
Nizatidine (Axid) potency=10

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19
Q

H2 blockers are rapidly absorbed orally, have minimal first pass metabolism, and cross both BBB and placenta. T/F

A

False. These drugs have extensive first pass metabolism and therefore are given at high doses

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20
Q

How are H2 blockers affected by pts with renal dysfunction

A

extends half life of drugs, so you shoud decrease the dose

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21
Q

What are clinical uses of H2 blockers

A

Treatment of duodenal ulcers
Allergy prophylaxis
Pre op med

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22
Q

What effects do H2 blockers have when given preop?

A

decrease gastric volume

INcrease gastric pH

23
Q

What are most common H2 blocker side effects?

A

diarrhea
headache
fatigue
malaise

24
Q

Prolonged use of H2 blockers may ______ gastric barrier to bacteria

A

weaken

25
Q

Which H2 blocker binds and inhibits cytochrome p450?

A

cimetidine–It may also delay clearance of lidocaine due to a decrease in hepatic blood flow

26
Q

How does cromolyn affect histamine? How is it used?

A

Inhibits antigen-induced release of histamine from mast cells
Used as a phrophylaxis for bronchial asthma and is administered by inhalation

27
Q

What type of drugs are omeprazole, protonix and prevacid?

A

H+ pump inhibitors

28
Q

How do H+ pump inhibitors compare to H2 inhibitors?

A

Work longer (up to 24 hours) and give better results than H2 blockers

29
Q

How are H+ pump inhibitors used for anesthesia?

A

as a pre op medicine they increase gastric pH, decrease gastric fluid volume. They must be given > 3 hours prior to surgery

30
Q

Serotonin causes vasoconstriction in _________, _________, and ___________

A

cerebral, coronary and pulmonary

31
Q

90% of serotonin is found in enterochaffin cells of _________, the rest is in ________ and _________

A

GI tract

CNS and platelets

32
Q

Serotonin is Oxidized by ___________ and ________, and taken up by _________

A

liver and lungs

platelets

33
Q

What does 5 HT1 cause. What is a drug that agonizes these receptors?

A

Cerebral vasoconstriction

Sumatriptan (Imitrex) revers middle cerebral artery vasodilation and improves migraine and cluster headaches

34
Q

How do 5HT2 antagonists work?

A

Kentanserin attenuates vasoconstriction, bronchoconstriction and platelet aggregation, and acts as an alpha blocker

35
Q

What conditions may be treated by 5-HT3?

A

N/V
appetite
addiction
pain anxiety

36
Q

How can you tell if a drug is a 5 HT3 antagonist?

A

ends in setron

37
Q

What are side effects of Zofran?

A

headache
diarrhea
increased liver enzymes

38
Q

How do antacids work?

A

acid+base=salt

at pH>5 pepsin is inactivated, LES tone is increased, and gastric contents are pushed forward

39
Q

what are characteristics of sodium bicarbonate?

A

highly soluble
rapid action in stomach for a brief duration
May cause alkolosis
Avoid in renal and heart pts. May increase sodium load

40
Q

Magnesium hydroxide can cause acid rebound, and has a laxative effect. t/f

A

false. no acid rebound

41
Q

What may happen with high doses of magnesium hydroxide?

A

Neuro/NM effects

42
Q

Calcium carbonate is rapidly absorbed, can cause and acid rebound, and may cause hpercalcemia and metabolic alkalosis with chronic use. t/f

A

true

43
Q

how is aluminum hodroxide absorbed?
what may it deplete?
HOw does it affect gastric emptying?

A

Minimally
phosphate
decreased

44
Q

How do antacids affect other drugs?

A

increased delivery of PO medicines but decreased bioavailability

45
Q

Antacids decrease incidence fo regurgitation and aspiration. T/f

A

f. no effect

46
Q

What is an example of an antacid that may be given pre op?

A

bicitra (sodium citrate and citric acid)

47
Q

How does sucralfate work? what is it used for?

A

reacts with HCL in stomach to form a viscous paste which forms a protective barrier in stomach. Used to treat duodenal and stomach ulcers

48
Q

What are the effects of metoclopramide?

A

increases gastric emptying
increase LES tone
Relaxes pylorus and duodenum when the stomach contracts

49
Q

What are side effects of metoclopramide. Which pts should they be avoided in?

A 
may cause sedation, agitation, and dysphoria
-give slowly or post induction
Most common
-dry mouth
-abdominal cramping
-dysrhythmias
-extrapyramidal effects
Rare
-Hirsutism
-Macropapular rashn
With chronic use there is a prolactin association leading to  breast enlargement and menstrual irregularities
Don't give to GI obstruction
Since it is a dopamine antagonist it should be avoided in parkinsons pts
50
Q

how is metoclopramide eliminated?

A

renally

51
Q

What are clinical uses of metoclopromide?

A

pre-op adunct
anti-emetic
gastroparesis therapy
symptomatic GERD

52
Q

Which patient needs metoclopramide?

A 
full stomach
trauma
obese 
diabetic
parturient
53
Q

What are effects of Domperidone?

A 
dopamine antagonist
stimulates peristalsis
increases LES tone
Increase gastric emptying
No cholinergic or central effects like reglan
54
Q

What is cisapride (propulsin)?

How does it work?

A

gi Prokinetic

causes an increase in ACh and PS activity which increases gastric emptying. used for pts with gastroparesis

Anesthesia Pharmacology (25 decks)

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